The present invention relates generally to a vehicle suspension system including viscously activated tension dampers employed on tension cables to dampen the roll of a vehicle.
Vehicles are commonly equipped with suspension systems for absorbing road shock and other vibrations, while providing for a smooth and comfortable ride. A suspension component, such as a stabilizer bar, is often used to increase roll rigidity and improve the steering stability of the vehicle. The stabilizer bar is generally attached to the lower control arms of the suspension system to control sway as the vehicle turns.
As a vehicle turns, the body of the vehicle rolls to the outside of the turn. The suspension components on the outside of the turn are generally compressed, while the suspension components on the inside of the turn are generally extended. The stabilizer bar counters this motion by pushing up on the suspension components collapsed through torsion in the stabilizer bar, leveling the vehicle.
One drawback to prior art stabilizer bars is the xe2x80x9cdead-bandxe2x80x9d area at the transition point where the suspension moves from one direction to the other. The stabilizer bar acts as a spring to assist in returning the vehicle to a level position. However, if there is not sufficient damping in the suspension, the stabilizer bar tends to overshoot the level position. Damping is commonly added to the shock absorbers or struts to counteract this roll. However, a drawback to adding more damping is that harshness is introduced into the ride of the vehicle.
In prior vehicle suspension systems, a constant tension damper which is not viscously dampened is used on tension cables positioned in the vehicle suspension system. As suspension members, such as lower control arms, rotate, a slider in the tension damper compresses a compressible member in response to tension in the tension cable to dampen vehicle roll. Additionally, in the prior systems, each of the tension cables attach at the bottom of one suspension member and attach at the top of the opposing suspension member on the opposite side of the vehicle. One drawback to this arrangement is that it is not practical on most of today""s suspensions.
Hence, there is a need in the art for an improved vehicle suspension system using viscous tension dampers employed on intersecting tension cables.
This invention relates to a vehicle suspension system using viscous tension dampers employed on intersecting tension cables.
The vehicle suspension system of the present invention includes a first and a second lower control arm, each rotatable about a pivot point. A pair of tension cables positioned around cams are attached to each of the lower control arms and pivot with the cams at the pivot points. The pair of tension cables are each attached to a first and a second attachment point, a cable axis passing through both of the attachment points. A first tension cable attaches at the first attachment point on the first lower control arm, passes on a first side of the cable axis, crosses over to an opposing second side of the cable axis, and attaches at a second attachment point on the second lower control arm. The second tension cable attaches at the first attachment point, passes on the second side of the cable axis, crosses over to the first side of the cable axis, and attaches at the second attachment point. A tension damper is employed on each of the tensions cables and react in response to tension applied to the respective tension cables as the control arms rotate about the pivot points in response to vehicle roll to dampen the roll of the vehicle.
In the preferred embodiment, each tension damper includes a cylinder containing a fluid and a piston including at least one orifice attached to a rod. A first side of the tension cable is attached to the rod, and a second side of the tension cable is attached to the cylinder. The piston divides the cylinder into a first compartment and a second compartment. As the vehicle turns, the control arms and cams pivot about the pivot point, increasing the tension in one of the tension cables. As tension increase, the tension cable pulls on the rod and the attached piston. As fluid is contained in the cylinder, the fluid creates resistance to the movement of the piston. As the tension cable continues to pull, fluid is directed through the orifice from one compartment to the other compartment, damping the roll of the vehicle. A spring mechanism returns the tension damper to the original position after the vehicle is leveled.
Alternatively, the fluid can be either electro-rheological or magnetic-rheological. In this embodiment, a sensor detects when the roll of the vehicle needs to be controlled. The sensor generates a signal in response to this signal, applying either an electric or magnetic field to the fluid to increase fluid viscosity and providing additional resistance in the tension damper.
In another embodiment, the tension damper actively controls damping. The sensor generates a signal which controls both the number and the size of the orifices in the piston.
Accordingly, the present invention provides a vehicle suspension system using tension dampers employed on intersecting tension cables.
These and other features of the present invention will be best understood from the following specification and drawings.